The present invention relates to a method of and apparatus for heating circulating air and more particularly air which circulates in drying equipment by utilizing the thermal energy obtained in the process of thermal incineration or oxidation as a source of heat to preheat an exhausted portion of the circulating air and directly or indirectly supply heat to the remaining circulating air in the drying chamber; thus, maximizing the return of the thermal energy contained in the incinerated gases and fuel economy.
In the prior art, it is known to heat the circulating air in drying equipment and especially in automotive painting installations, so that the drying process may be accomplished in a short time period. A minimum drying time allows for substantial cost savings and for an efficient production line process. It is known to exhaust a portion of air from the drying equipment and direct it to a burner of a thermal incinerator, whereupon the heat of the incinerated gases is partially used to directly or indirectly heat the remainder of the circulating air in the drying equipment.
The disadvantage with the prior art method is that is does not utilize all of the thermal energy still potentially to be derived from the heated incinerated gases; because thus, of not using a preheat exchanger, making the prior art method costly and inefficient.
This disadvantage makes the prior art process expensive, difficult and cumbersome to carry out, and the apparatus unsuitable for production line techniques.